API 17D – Specification for Subsea Trees and WellheadsDifferential Pressure Use in Design of Subsea Equipment12-13 June 2012

2

• Subsea Equipment Pressure Ratings - API TECHNICAL REPORT 17TR4 - JANUARY 2012

• 3.1.1 - design pressure- The maximum differential between internal

pressure and external pressure during operating conditions at each cross-section. (API 1111)

• 3.1.2 - rated working pressure- The maximum internal pressure a piece of

equipment is designed to contain and/or control. (API 17D, API 6A)

API 17D – Use of Differential Pressure in Subsea Equipment Design

3

Document objectives:

• define the framework for the use of differential pressure as well as broadly definition of paths to:- determine standards for designing equipment

using differential pressure;- how to rate the equipment for differential pressure

service; and- determine how to validate (test) the design of the

equipment.

API 17D – Use of Differential Pressure in Subsea Equipment Design

4

• VME stress = f(∆P); not magnitude of Pi or Po

• Principal stress or individual stress component failure criteria = f(Pi and Po)

API 17D – Use of Differential Pressure in Subsea Equipment Design

5

• Summary of TR4• All loads and conditions that may realistically occur must be considered (including

accidental )

• Limits must be defined for materials and loads to provide protection against the appropriate types of failure.

• Limit load failure based upon VME stress is affected by differential pressure and external applied loads.

• Localized stress concentration areas, such as areas of discontinuity and areas of high mean and alternating stresses, are normally where fatigue failures occur.

• Principal stresses are important in analyzing failure from cyclic loading.

• Other system failures, such as non-metallic seals, may be the weak link in the system instead of the pressure vessel body.

API 17D – Use of Differential Pressure in Subsea Equipment Design

66

ATP Oil & Gas Corporation (NASDAQ: ATPG)

ATP Oil & Gas Corporation4600 Post Oak Place , Suite 100Houston, TX 77027-9726713-622-3311

ATP Oil & Gas (UK) LimitedVictoria House, London Square, Cross LanesGuildford, Surrey GU1 1UJ United Kingdom44 (0) 1483 307200

ATP Oil & Gas (Netherlands) B.V. Water-Staete GebouwDokweg 31 (B)1976 CA IJmuidenThe Netherlands 31 (0) 255 523377

ATP East Med B.V. 15 Aba Even StreetHerzliya Pituach 46725Israel

www.atpog.com

ATP Innovator

ATP Titan Octabuoy